This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Vehicles using electric power for all or a portion of their motive power may provide numerous advantages as compared to traditional vehicles powered by internal combustion engines. For example, vehicles using electric power may produce fewer pollutants and may exhibit greater fuel efficiency. In some cases, vehicles using electric power may eliminate the use of gasoline entirely and derive the entirety of their motive force from electric power. As technology continues to evolve, there is a need to provide improved power sources, particularly battery modules, for such vehicles. For example, it is desirable to provide effective cooling to the battery modules to prevent premature aging of individual battery cells within the battery module, while simultaneously minimizing the cost of the battery module. It is also desirable to provide a cooling system design that can utilize cabin air as an effective coolant.
Vehicles using electric power for at least a portion of their motive force may derive their electric power from the multiple individual battery cells packaged into the battery modules. The individual cells may utilize lithium-ion chemistry and may be packaged into prismatic casings. The battery modules may contain the multiple individual cells within a generally rectangular housing. As the individual cells are charged and discharged, they may generate heat due to Joule heating caused by current flowing through the internal resistance of the cells. In addition, the individual cells may be subjected to heating via exothermic chemical reactions occurring within the cells. Further, in some cases, elevated ambient temperatures may add heat to the cells via conduction, convection, and/or radiation. These (and other potential) sources of thermo-electrical, thermo-chemical, and environmental heating may cause increased localized temperatures of the cells. The increase in temperature may be aggravated by the tight packaging of multiple cells within the confined space of the battery module housing. Increased temperatures may increase the rate of chemical reactions, cause physical distortion (e.g., swelling, short circuits, open circuits), that may exponentially age the cells and the battery module. Accordingly, it would be desirable to provide an effective cooling system to draw excess heat away from the module, thereby creating an isothermal temperature distribution along the cells in a module or battery pack to preserve the cells.
Further, it may be advantageous to utilize air as the coolant within the cooling system. Typical cooling systems may use a liquid coolant looped from the engine to the battery of the vehicle. However, liquid coolants may be disadvantageous in vehicular systems, which heavily rely on electronic components. For example, a liquid coolant leak may damage any electronic components contacted. Further, liquid coolants are more dense than air, resulting in increased weight and cost associated with liquid coolant based systems. Additionally, use of a liquid coolant requires an additional fluid stream within the vehicle, whereas air may be cycled throughout the cabin and the cooling system, reducing the number of fluids circling through the vehicle. Accordingly, it would be desirable to provide a cooling system that effectively uses air to create the isothermal temperature distribution along the cells.